Some surgical operations, for example, hip or knee arthroplasty, require at least one bone cut at the level of the head of a long bone to arrange a prosthesis. Bone cutting is performed by means of a cutting tool, for example, a miller or an oscillating saw, maintained in position by a cutting guide attached to the bone. Generally, several bone cut must be successively performed in distinct planes at the level of a same bone head. It is then necessary to accurately determine the relative positions between the cutting planes, while ensuring a surface state of sufficient quality for each cutting plane.
U.S. Pat. No. 4,457,307 describes a device for guiding a cutting tool to perform successive cuttings to arrange a knee prosthesis. The device comprises a seat intended to be fastened on the femur diaphysis. A cutting guide is pivotally assembled on arms, themselves pivotally assembled on the seat. The guide can then be displaced with respect to the seat to define the cutting planes. A saw is maintained by the guide as the bone cuttings are performed. A disadvantage of such a device is that it is relatively bulky.
U.S. Pat. No. 5,653,714 describes a device for guiding a bone cutting tool to perform successive bone cuttings along distinct cutting planes exhibiting a reduced bulk.
The present invention aims at obtaining an alternative cutting guide adapted to the performing of a bone cutting, or of several successive bone cuttings along different cutting planes, exhibiting a reduced bulk.
The present invention also aims at obtaining a cutting guide of particularly simple structure and kinematics.
To achieve these objects, the present invention provides a device for guiding a cutting tool capable of cutting bone portions at the level of the head of a bone, comprising a seat intended to be fastened at the level of said head defining a first rotation axis; means for adjusting the position of the first rotation axis with respect to said seat; an arm, one end of said arm being pivotally assembled on said seat according to the first rotation axis; and a guide intended to support the tool and pivotally assembled on the arm according to a second rotation axis (Δ).
According to an embodiment of the present invention, the guiding device comprises two seats intended to be fastened at the level of said head in substantially opposite fashion with respect to said head and defining a first rotation axis; means for adjusting the position of the first rotation axis with respect to the seats; two arms, one end of each arm being pivotally assembled on a seat according to the first rotation axis; and a guide extending substantially transversally to said head, and pivotally assembled at two ends on the arms according to a second rotation axis, the maximum swinging angle of the guide around the first rotation axis being greater than 100 degrees.
According to an embodiment of the present invention, one of the arms is connected to a seat by a pin joint, the adjustment system being arranged between said seat and said pin joint and being capable of modifying the position of said pin joint with respect to said seat according to two directions substantially tangent to said head.
According to an embodiment of the present invention, the device comprises a first actuating gear capable of rotating at least one arm around the first rotation axis and a second actuating gear capable of rotating the guide around the second rotation axis.
According to an embodiment of the present invention, the device comprises a connection element connecting the two seats by at least partially surrounding said head.
According to an embodiment of the present invention, the adjustment means are arranged between one of the seats and the connection element.
According to an embodiment of the present invention, the device comprises means for displacing one of the seats with respect to the connection element in a direction transversal to said head.
According to an embodiment of the present invention, each seat comprises at least one pick intended to come in contact with said head.
According to an embodiment of the present invention, the guide comprises at least one opening for guiding the cutting tool.
According to an embodiment of the present invention, the cutting tool is a mill.
According to an embodiment of the present invention, the cutting tool is an oscillating saw.